1. Field of the Invention
The present invention relates to a developer container for replenishing a developer to a developing device of an image forming apparatus such as a copying machine, printer or the like.
2. Description of the Prior Art
An image forming apparatus is provided with a developer container removable therefrom for periodically replenishing a developer to a developing device. The developer container, as disclosed in U.S. Pat. No. 5,296,900, U.S. Pat. No. 4,641,945 or the like, is a cylindrical bottle having a spiral rib on the internal surface and an outlet opening on the side surface at the one end of the bottle, in which the developer is contained. The open end of the container is sealed with a cap. The outlet opening of the container is closed by a sealing film glued to the edge of the outlet opening.
The developer container is mounted horizontally on the image forming apparatus such as a copying machine. Then, the sealing film is tore off. The rotation of the container allows the developer within the container to move toward the end of the container along the spiral rib and to flow out through the outlet opening. Thereby, the developer is periodically replenished to the developing device at every one rotation of the developer container.
The developer container, however, has a disadvantage that the developer is not replenished stably. The reason is that although a constant quantity of developer is replenished through the outlet opening while a large quantity of developer is contained within the container, the quantity of the developer replenished from the container becomes smaller as the developer contained within the container reduces gradually.
Therefore, some type of developer container for stably replenishing the developer to the developing device has been proposed so far.
Japanese Laying-open Patent Publication No. 6-102,758 discloses a developer container which is provided with an enclosure portion surrounding the outlet opening of the container. The enclosure portion has a opening part such that a constant quantity of the developer scooped by the opening part of the enclosure portion can be dropped through the outlet opening and replenished to the developing device. The developer container has a disadvantage that the construction of the enclosure portion is complicated and is not suitable for a blow molding method. The container has a further disadvantage that a large quantity of the developer remains within the container without being scooped by the enclosure portion when the developer is running short.
U.S. Pat. No. 5,296,900 (especially in FIG. 21) discloses a developer supplying container on the side surface of which an outlet opening is disposed such that the opening is close to the spiral rib at the terminal end thereof. The container is intended to effectively lead developer remaining in the container to the outlet opening along the spiral rib. In this container, however, all the developer is not always dropped through the outlet opening because a part of the developer away from the spiral rib is not led to the outlet opening. This means that the quantity of replenishing developer becomes unstable and that it is not possible to eliminate the above described disadvantage i.e. a waste of developer due to the remains within the container.
In the aforementioned developer containers, a vibration or swing motion perpendicular to the longitudinal axis of the container is applied to the container during the rotation thereof such that the developer within the container flows out smoothly through the outlet opening. Such developer containers have a disadvantage that it is necessary to increase the rotational torque of the container.
Moreover, the above developer containers have a disadvantage that the cylindrical body is likely to cause the container to roll when the container is placed on the table or floor at the time of maintenance or inspection, whereby the developer is spilt thereon through the outlet opening to soil the surroundings.